This disclosure generally relates to systems and methods for tracking a moving target and, in particular, relates to short-range point defense systems for the defense of a single object or a limited area, e.g. a ship, building or an airfield, against incoming artillery, rockets, mortar rounds and missiles.
Radar devices, such as real beam radars, laser radars, sonar, and the like, transmit signals, such as electromagnetic or sonar signals, that advantageously reflect off targets and are received by the radar device to provide data related to the position of the target. Targets detected by radar devices may be stationary or moving objects. Radar devices typically comprise an antenna that transmits and receives the radar signals. Signals received by the radar device provide target data, such as the target's distance from the radar device or size. Some radar devices, such as a radar device used for short-range point defense, typically rotate the antenna through 360 degrees to detect targets within the area swept by the antenna, such as an area proximate the short-range point defense radar device.
To track a moving target, radar devices typically detect the motion of the target based upon Doppler information provided by the radar signals that are reflected off the moving target. The movement of the target in a radial direction, relative to the radar device, causes the radar signals that reflect off the moving target to return to the radar device with a frequency that is different than the frequency that was transmitted by the radar device. Specifically, the radial movement of the target changes the frequency of the radar signal an amount that is proportional to the relative velocity of the target such that the change in frequency of the radar signal may be used to determine the location and speed of the moving target and to accordingly track the moving target.
While development of active electronically scanned array (AESA) technology offers the opportunity to design radar systems for various short-range anti-missile and counter rocket, artillery and mortar (CRAM) applications, the technology of multi-beam FMCW offers some promise of lower cost, more accurate radars compared to AESA technology.
Except for widely separated bistatic systems, radar designers typically think of frequency-modulated continuous wave (FMCW) radars for extremely short-range operation and against a target set without small targets. In fact, FMCW radar technology has transcended most of these performance barriers, but the technology is still used in a limited set of applications.
FMCW radar has multiple advantages compared to pulsed radars, including at least the following: (a) much lower peak power than pulsed radars; (b) much reduced receive digital bandwidth requirement compared to pulsed radars; (c) much higher range resolution compared to pulsed radars; and (d) design freedom to separate transmit and receive antennas. Likewise multi-beam digital beamforming has advantages compared to pulsed radar, including at least the following: (a) searches the entire field of regard in each sweep; and (b) greatly improved tracking capability for multi-beam systems.
In view of the foregoing advantages, it would be desirable to provide a multi-beam FMCW radar system suitable for use as a short-range point defense system.